A mother and daughter were witness to a cat being killed after a firework was attached to it.
The firework exploded, killing the animal instantly, in front of the pair at about 6pm in Shelley Road, Wellingborough, on Saturday (November 10).
The officer investigating the incident, PC Mark Jones, said: "This is an unbelievably cruel act and we are very keen to hear from anybody who has any information which will lead to the identification of the perpetrators.
"Not only was it horrific for the poor animal involved, the witnesses and owners of the cat are understandably very distressed.
"I urge anybody with any information to get in touch so that we can identify and deal with whoever is responsible for this horrible act.
"Contact me on 101 and ask for Wellingborough SCT, or email me via our website.
"All contact will be strictly confidential."
Witnesses to this incident, or anyone with information, should call Northamptonshire Police on 101 - alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.